JPH09203501A - Small-sized once-through boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable compactification by preventing burnout by overheat of a water pipe, especially the burnout in the periphery of the stoke port of a burner, and enlarging heat load of a combustion chamber more than a conventional boiler. SOLUTION: A regenerative of burner system, which is so constituted as to supply air A for combustion through a heat storage body 22 heated with the heat of combustion gas by performing the supply of air A for combustion and the discharge of combustion gas E through the heat storage body 22, switching the flow of the combustion gas E and the air A for combustion to the heat storage body 22, is arranged at least one system or more in a combustion chamber 1. Then, a group of water pipes 4...4 are installed apart from the wall face 3 of the combustion chamber, and a passage 12 is made between the rear of the group of pipes 4 and the wall face 3 of the combustion chamber, while communication ports 10 and 11 where combustion gas passes are made each between adjacent water pipes 4 at the top and bottom of the group of the water pipes 4...4 so that a part of the combustion gas C may pass the passage 12 behind the group of the water pipes 4...4, and a part of combustion gas flows in the passage 12 from the communication port 11, and goes up, and flows in the combustion chamber 1 again from the upper communication port 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a small once-through boiler. More specifically, the present invention relates to improvements in the combustion chamber of small once-through boilers.

[0002]

2. Description of the Related Art In a conventional combustion chamber of a small once-through boiler, for example, as shown in FIG. 6, water tubes 103 and 104 are doubled inside a furnace wall (inner peripheral wall) 102 of a vertically long cylindrical furnace body 101. By arranging in a ring shape, a heat transfer surface is formed and the furnace wall 102 is cooled. The water pipe 103 arranged on the outside is connected to the fins 109 as shown and half-filled in the furnace wall 102, or, although not shown, it is arranged without fins without gaps and half-filled, or It is installed in contact with the furnace wall 102. Further, the water pipe 104 arranged on the inner side is installed with a gap to the extent that exhaust gas flows between the water pipe 104 on the outer side. Inner water pipe 104 and outer water pipe 10
3 are arranged annularly and are connected to each other by fins 109 or are densely arranged, so that the inner water pipe 10
The gap between the water pipe 4 and the outer water pipe 103 is configured as a flow path 105 through which exhaust gas flows. Therefore, in the combustion chamber structure of this boiler, the inner surface of the inner water pipe 104 functions as a radiant heat transfer surface, and the inner surface of the outer water pipe 103 and the outer surface of the inner water pipe 104 convective heat transfer surface. Function as.

In the conventional general boiler, a communication port 106 connected to the flow path 105 is provided between the water pipes 104, 104 near the bottom of the combustion chamber, and exhaust gas is exhausted between the water pipes 103, 103 near the top of the combustion chamber. Exhaust ports 108 connected to the means 107 are respectively provided, and the combustion gas generated in the combustion chamber 110 is supplied from the communication port 106 at the bottom of the combustion chamber to the inner water pipe 1.
04 and the water pipe 103 on the outside, and is introduced so as to be discharged from the exhaust port 108 at the upper part of the boiler. That is, combustion of the burner 111 causes combustion chamber 11
While discharging the combustion gas generated in 0 from the communication port 106 at the bottom of the combustion chamber through the inner water pipe 104 and the outer water pipe 103, heat is exchanged with the boiler water by radiant heat transfer and convective heat transfer to obtain steam. I am trying. The radiant heat transfer section has a high flame temperature and a high furnace heat load, but the heat of the combustion gas cannot be fully utilized only in this section. Therefore, in the conventional boiler, if the heat of the combustion gas is not recovered by the convection heat transfer section between the inner water tube group and the outer water tube group only by the radiant heat transfer section, the exhaust gas temperature becomes extremely high and the heat is given to the surrounding environment. A large convection heat transfer section is usually installed side by side because the impact on the boiler becomes large and the thermal economy of the boiler deteriorates. For example, the combustion gas obtained by burning the burner 111 at the top of the boiler is lowered to about 1200 ° C. at the bottom of the boiler by the radiant heat transfer in the combustion chamber 110, and the inner water pipes 104 group and the outer water pipe 103 group are separated. While passing through the convection heat transfer section, the temperature is lowered to about 300 ° C. and then exhausted.

[0004]

However, the conventional combustion chamber structure has a problem that the combustion chamber heat load cannot be increased because the temperature of the combustion gas is highest near the burning port of the burner 111. That is, in the case of a once-through boiler, since water is heated and becomes steam while passing through the water pipe from the bottom to the top, the water / hot water region 112, the boiling region 113, and the dry-out are provided in the water pipes 103 and 104. Vapor regions 114 are formed in order from bottom to top. Therefore, the steam region 114 is located near the burning port of the burner 111. However, water or steam has a small heat transfer coefficient, and even if a large amount of heat is applied, the water or steam does not accept it, and the water pipe exposed to the flame is overheated. Therefore, in order to prevent the water pipe from being burnt out, the combustion gas temperature in the vicinity of the burner port of the burner 111 must be lowered. Conventionally, the heat load in the combustion chamber was reduced and the required steam amount was secured by enlarging the boiler. .

The present invention provides a small-sized once-through boiler capable of preventing burnout due to overheating of a water tube, especially burnt around the burner opening, and having a larger heat load in the combustion chamber than that of a conventional boiler, thereby enabling compactification. The purpose is to provide.

[0006]

In order to achieve such an object, a small once-through boiler of the present invention supplies combustion air and discharges combustion gas through a heat storage body and supplies combustion gas and combustion air to the heat storage body. At least one heat storage type burner system in which combustion air is supplied through a heat storage body heated by the heat of combustion gas by relatively switching the flow is arranged in the combustion chamber, and the water pipe group is separated from the wall surface of the combustion chamber. Installed to form a flow path between the back surface of the water tube group and the wall surface of the combustion chamber, while forming a communication port through which the combustion gas passes between the water tubes adjacent to the upper and lower ends of the water tube group. A part of the combustion gas passes through the flow passage on the back side of the water pipe group, and a part of the combustion gas flows into the flow passage through the lower communication port, rises, and flows into the combustion chamber again through the upper communication port. I have to.

Therefore, the radiant heat of the combustion gas injected into the combustion chamber heats the inner surface of the water pipe facing the combustion chamber. Then, a part of the combustion gas reversely rises at the bottom of the furnace and is discharged as it is through the heat storage body of the heat storage type burner system. Further, the remaining combustion gas flows from the communication port at the bottom of the combustion chamber to the flow path side at the back of the water pipe, and again flows into the combustion chamber from the communication port at the top. Then, a part of the heat is recirculated along with the combustion air and a part of the heat is exhausted through the heat storage body of the heat storage type burner system. As a result, the boiler water flowing in the water pipe is heated on the inner heat transfer surface by the radiant heat transfer from the flame and the combustion gas, and at the same time on the outer heat transfer surface, the flow between the water tube group and the combustion chamber furnace wall is increased. It is heated by convective heat transfer from the combustion gases flowing through the passage. Moreover, a part of the combustion gas flowing into the combustion chamber again from the upper communication port is accompanied by the combustion air injected into the combustion chamber to increase the volume of the combustion gas, and even if the combustion chamber is deep, the flame rises. It is possible to allow the combustion gas to reach the bottom of the combustion chamber and to heat the bottom of the combustion chamber by radiant heat transfer. At the same time, the NOx is reduced by recirculating the combustion gas at this time. Further, the flame and the combustion gas near the burner firing port are diluted with the gas used for the radiant heat transfer and the convective heat transfer, and the temperature of the flame and the combustion gas is averaged.

Further, when the high temperature combustion exhaust gas passes through the heat storage body and is exhausted, the sensible heat thereof is directly recovered by the heat exchange in the heat storage body. Then, the heat recovered in the heat storage body is used for preheating the combustion air with extremely high efficiency by direct heat exchange and is returned to the combustion chamber again. Since the temperature of the combustion air can be set to a high temperature close to the temperature of the combustion exhaust gas flowing out to the heat storage body, combustion can be maintained with a small amount of fuel using this high temperature combustion air and the temperature in the combustion chamber can be rapidly raised.

Here, the small once-through boiler of the present invention is a heat storage type in which fuel is continuously injected from the same fuel nozzle without switching, and the flow of combustion exhaust gas and combustion air to the heat storage body is relatively switched. It is preferred to use a burner system. In this case, combustion is not interrupted only by switching the flow of combustion exhaust gas and combustion air without switching fuel. The combustion air and the fuel that are directly injected into the combustion chamber are mixed after being injected into the combustion chamber, but the combustion air has an extremely high temperature (for example, 1
Since the temperature is close to 000 ° C or higher), stable combustion occurs.

Further, the heat storage type burner system has a heat storage body which is evenly divided into three or more chambers in the circumferential direction and allows a fluid to pass axially through each chamber, and a heat storage body which penetrates through the center of the heat storage body. Between the inlet / outlet means and the heat storage body, the inlet / outlet means having a fuel nozzle for directly injecting fuel into the fuel cell, an air supply chamber connected to the combustion air supply system, and an exhaust chamber connected to the combustion gas exhaust system. While being interposed to shut off between the heat storage body and the inlet / outlet means, it continuously or intermittently rotates to divide the exhaust chamber and the air supply chamber of the inlet / outlet means into three or more compartments. It is composed of a switching means for sequentially communicating with each other without overlapping with each other, and continuously injects fuel into the combustion chamber and directly moves high temperature combustion air from the heat storage body to the combustion chamber around the injection portion in the circumferential direction. It is preferable to inject.

In this case, the air supply chamber and the exhaust chamber of the inlet / outlet means are communicated with different chambers / compartments of the heat storage body through the switching means which rotate intermittently or continuously, and the combustion air and the combustion exhaust gas are separated from each other. They flow in the heat storage body at the same time without crossing each other. Therefore, the combustion air and the combustion exhaust gas flow in the same chamber / compartment of the heat storage body at different times,
For example, combustion air will flow into the heat storage body after flowing the combustion exhaust gas, and the combustion air is preheated to a high temperature close to the temperature of the combustion exhaust gas by using the heat of the heat storage body heated by the passage of the combustion exhaust gas. Supplied. Further, when the heat of the heat storage body is lowered, the injection position of the combustion air is moved in the circumferential direction by the rotation of the switching means to utilize the heat storage body of the combustion air supply means that has exhausted the combustion gas until now. Supply combustion air. Therefore, the flame formed by the combustion air supplied by moving the place so as to rotate around the fuel nozzle and the fuel injected at the center rotates in the circumferential direction in the combustion chamber to make the combustion chamber uniform. Heat to.

Further, the small once-through boiler of the present invention is a heat storage type burner system in which a pair of burners each equipped with a heat storage body are alternately burned in a short time and exhausted through the heat storage body of the burner which is not burning. Preference is given to using. In this case, since the flame position changes frequently, the temperature distribution in the combustion chamber can be made more uniform.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 5 show an embodiment of a small once-through boiler according to the present invention. This small once-through boiler is, for example, a combustion chamber 1
A group of water pipes 4, 4, ..., 4 are installed apart from the inner peripheral wall surface 3 of the vertically long cylindrical furnace body 2 that forms the. A group of water pipes 4, 4, ..., 4 are connected by a lower header 5 and an upper header 6. Further, the upper header 6 and the lower header 5 are connected via a gas-liquid separator 7. The boiler water 15 supplied from the lower header 5 is heated while rising in the water pipes 4, ..., 4 and is boiled and becomes vapor to be collected in the upper header 6 and then transferred to the gas-liquid separator 7. Only steam is taken out in the gas-liquid separator 7, and hot water is supplied again as boiler water 15 through the reflux pipe 14. A cylindrical flow path 12 is formed between the inner peripheral wall surface (combustion chamber wall surface) 3 of the furnace body 2 and the tube wall formed by a large number of water tubes 4 ,.
In the vicinity of the upper and lower ends of the water pipe 4, that is, in the vicinity of the furnace top portion 8 and the furnace bottom portion 9, the flow passage 12 and the combustion chamber 1 inside the pipe wall are provided.
An upper communication port 10 and a lower communication port 11 are provided that allow the combustion gas C to enter and exit by communicating with the above. These communication ports 10 and 11 are formed, for example, as shown in FIG. 3, by narrowing the diameters of the upper and lower ends of the water pipe 4 to form a gap between adjacent water pipes. The water pipes 4 are arranged with almost no gap except at both ends, and the flow passage 12 communicating with the inside of the combustion chamber 1 through the upper communication port 10 and the lower communication port 11 has a combustion chamber wall surface 3
To form a tube wall surrounding the combustion chamber 1. Further, the communication ports 10 and 11 are formed, for example, as shown in FIG. 4, by fixing fins 13 to a portion of the water pipe 4 excluding the upper end and the lower part, and connecting the fins 13 with each other by welding or riveting. . In any case, the upper communication port 10 is provided between the water pipes 4 and 4.
With the exception of the lower communication port 11, there is almost no gap, but this is not intended to eliminate the gap at all, and there is no problem even if there is a gap and a leak occurs.

The furnace body 2 is usually formed by lining the inside of a steel plate casing with a refractory heat insulating material or providing an air cooling layer. The furnace top 8 of the furnace body 2 is equipped with a heat storage type burner system 20 as a heat source. In the present embodiment, one set of heat storage type burner system 20 is provided in the combustion chamber 1, but two or more sets of burner systems may be equipped depending on the case.

In this embodiment, a case of a heat storage type burner system which constitutes one burner is shown. In this heat storage type burner system 20, a fuel nozzle 21 that directly injects the fuel F into the combustion chamber 1 is penetrated through the center of the heat storage body 22, and the combustion air A that has been heated to a temperature substantially parallel to the periphery of the jet of the fuel F is used. Is to be jetted.

Here, the system for supplying the combustion air A and exhausting the exhaust gas E is basically indicated by reference numerals 30, 31, 32 in the present embodiment, for example, three or more chambers. Inlet / outlet means having a heat storage body 22 partitioned into three chambers through which a fluid can pass in the axial direction, an air supply chamber 23a connected to an air supply system 41, and an exhaust chamber 23b connected to an exhaust system 43. 23, the inlet / outlet means 23 and the heat storage body 22
Is interposed between the heat storage body 22 and the inlet / outlet means 23, and at the same time has a supply hole 25 and an exhaust communication hole 26 that are not present in the same section, either continuously or intermittently. The switching means 24 is configured to rotate to sequentially communicate the exhaust chamber 23b of the inlet / outlet means 23 and the air supply chamber 23a with any of the chambers 30, 31, 32 of the heat storage body 22.

The heat storage body 22 is not limited to a particular shape or material, but for heat exchange between the exhaust gas at around 1000 ° C. and the combustion air at around 20 ° C., for example, cordierite or mullite is used. It is preferable to use a honeycomb-shaped product manufactured by extrusion using ceramics as a material. Here, as the heat storage bodies 22, 22, it is preferable to use a material having a large heat capacity and a high durability, for example, a cylinder body having a large number of honeycomb-shaped cell holes formed of ceramics although the pressure loss is relatively low. In this case, the exhaust gas E
Even if the exhaust gas falls below the acid dew point temperature when the heat is recovered from the gas, the sulfur content in the fuel and its chemically modified substances are trapped in the ceramics, and the exhaust ducts in the downstream are not corroded at low temperature. Of course, the present invention is not particularly limited to this, and another heat storage material such as a ceramic ball or a nugget may be used. Further, the honeycomb-shaped heat storage body 22 is
In some cases, it may be made of a material other than ceramics, for example, a metal such as heat resistant steel. In addition, at medium to high temperatures around 500 to 600 ° C., it is preferable to use a metal such as aluminum, iron, or copper, which is relatively cheaper than ceramics. The honeycomb shape originally means hexagonal cells (holes), but in the present specification, not only the original hexagonal cells but also quadrangular or triangular cells are opened innumerably. Further, as described above, the honeycomb-shaped heat storage body 22 may be obtained by bundling tubes or the like without integrally molding. In the case of this embodiment, the heat storage body 22 has the distribution chambers 27, 2 arranged in front of and behind it.
It is divided into three chambers by 7 in the circumferential direction. For example, in the case of this embodiment, the three chambers 29a, 29
Due to the distribution chambers 27, 27 divided into b and 29c, a vacant chamber 30 in which the fluid does not flow in the heat storage body 22 as shown in FIG.
And a chamber 31 for flowing the exhaust gas E and a chamber 32 for flowing the air A. That is, since the heat storage bodies 22 themselves have a honeycomb shape formed of a set of cells each of which constitutes an independent flow path, the range partitioned by the partition 28 of the distribution chamber 27 is divided into one. Will form a chamber. When the distribution chamber 27 is provided, the communication holes 25, 2
It is possible to disperse the fluid flowing in via 6 and divide the fluid uniformly over the entire area of the heat storage body 22. Further, the shape of the heat storage body 22 is not particularly limited to the honeycomb shape shown in the figure, and although not shown, flat plate-shaped or corrugated plate-shaped heat storage material is radially arranged in a tubular casing, or a pipe-shaped heat storage material. May be filled in a cylindrical casing so that the fluid may pass in the axial direction. Further, in the present embodiment, the distribution chamber 27 allows the single heat storage body 22 to substantially form three chambers 30, 3.
However, the heat storage body 22 itself may be divided into three chambers in advance. For example, although not shown, a cylindrical casing, which is partitioned into three chambers in the circumferential direction by a partition wall and through which fluid can pass in the axial direction, is prepared, and each of these chambers has a spherical shape, a short tube, a short rod, or a thin rod. It may be configured by filling a lump of heat storage material such as a piece, a nugget shape, or a net shape. When using a heat storage material such as SiN that can be used at a much higher temperature than cordierite or mullite, it is not easy to mold it into a complicated honeycomb shape, but for simple pipe shapes, rods, balls, etc. It is easy to mold.

Here, the number of chambers divided into the heat storage body 22 is 1 for a chamber in which air A flows (hereinafter referred to as an air supply chamber) 32 and a chamber in which exhaust gas E flows (hereinafter referred to as an exhaust chamber) 31. As a set, at least one set is combined with one vacant chamber (a chamber in which a fluid does not flow) 30, and three chambers are the minimum number. Also,
The above-mentioned system is also configured by interposing the chambers 30 through which the fluid does not flow between the air supply chamber 32 and the exhaust chamber 31. In this case, the minimum number of rooms is four.

In this embodiment, the inlet / outlet means 23 is provided with a cylindrical partition wall 34 in a rectangular casing 33 so that the air supply chamber 23 is connected to the air supply system 41.
And an exhaust chamber 23b connected to the exhaust system 43. In the case of this embodiment, the supply chamber 2 is provided outside the partition wall 34.
3a, an exhaust chamber 23b is formed inside. In the case of the present embodiment, the switching means 24 is provided so as to rotate independently between the inlet / outlet means 23 and the distribution chamber 27. Partition wall 34
A seal member 35 is provided between the switch means 24 and the switch means 24 so as to allow the switch means 24 to rotate and to prevent fluid from leaking. The switching means 24 is rotatably supported by, for example, the partition wall 34 of the inlet / outlet means 23 and the fuel nozzle 21 at the center, and a gear 36 is formed on the periphery thereof, and a drive gear 37 arranged at a corner portion of the casing 33.
And is driven to rotate by the motor 38. Of course, the present invention is not limited to this, and it may be rotationally driven by a friction wheel, a chain, a belt or the like that is pressed against the peripheral edge of the switching means 24.

Air supply chamber 23a and exhaust chamber 2 of the entrance / exit means 23
3b and the chamber / compartment 32 of the heat storage body 22, which respectively correspond to
The switching means 24 that communicates only with 31 is formed of a disc orthogonal to the flow path, and is provided with one compartment of the heat storage body 22 and the air supply chamber 2.
At least one air supply communication hole 25 for communicating with 3a and at least one exhaust communication hole 26 for communicating one compartment with the exhaust chamber 23b are provided. The exhaust communication hole 26 and the air supply communication hole 25 must be such that the air supply communication hole 25 and the exhaust communication hole 26 cannot exist in the same chamber / compartment at the same time. Change from the front-most communication holes in the chambers / compartments one by one to the front chamber / compartment, and make sure that the sizes of the air supply communication holes 26 and the exhaust communication holes 26 do not overlap each other in the radial direction. It is provided so as to satisfy the three conditions that the size is such that all can be accommodated in one room at the same time when arranged. At this time, the air supply communication hole 25 and the exhaust communication hole 26 are set to have substantially the same size and the same shape, but the present invention is not particularly limited to this, and it is possible to supply air and exhaust gas. The size and shape may be changed, and if necessary, the size and shape may be changed for each communication hole. In general, the amount of air and the amount of exhaust gas are set to have a substantially balanced relationship, but in some cases, one communication hole may be set to be larger than the other communication hole.

The fuel nozzle 21 is arranged so as to penetrate the heat storage body 22 and be directly exposed or projected into the combustion chamber 1. The heat storage body 22 is surrounded by a casing 39 made of a refractory heat insulating material and housed in a metal casing 33. The fuel nozzle 21 is also held by the refractory heat insulating material casing 39. Here, the refractory insulation casing 39
Is provided with three injection ports 40, 40, 40 communicating with the respective chambers 29a, 29b, 29c of the distribution chamber 27 so as to open in the axial direction.

According to the boiler constructed as described above,
Make the entire circumference of the water pipe function as a heat transfer surface as follows,
Realizes uniform heating without unevenness.

The air A and the fuel F supplied into the combustion chamber 1 through the air supply system 41 and the fuel supply system 42 are mixed and burned. The combustion air A is supplied to the combustion chamber 1 after passing through the heat storage body 22 of the heat storage type burner system 20 which is warmed by the startup combustion and preheated to a high temperature. Also,
The fuel F is directly injected from the fuel nozzle 21 into the combustion chamber 1.

Here, the hot air A and the fuel F injected from the fuel nozzle 21 are separately injected into the combustion chamber 1,
It spreads to the combustion chamber 1 and is mixed away from the fuel nozzle 21. At this time, since the air A and the fuel F rapidly reduce their flow velocities and expand the mixing region over a wide range, they are conditions that are originally difficult to burn. However, since the air A itself has a high temperature of 700 to 800 ° C. or higher, it burns easily even under such conditions. That is, NO
Slow combustion with less generation of x occurs. The inner surface of the water pipes 4, ..., 4 facing the combustion chamber 1 is heated by the radiant heat of the combustion gas C generated by the slow combustion. After that, a part of the combustion gas C flows from the lower communication port 11 of the furnace bottom 9 into the flow passage 12 at the back of the water pipe 4 and rises (indicated by an arrow P), and then from the upper communication port 10 into the combustion chamber 1 again. The back surface of the water pipe 4 is heated by convection heat transfer before returning to. The remaining combustion gas C is reversed at the bottom 9 of the furnace, rises in the combustion chamber 1 (arrow B), and is discharged to the outside of the furnace from the injection port 40 of the heat storage chamber 31 connected to the exhaust system 43. It

Further, a part of the combustion gas flowing into the flow path 12 through the lower communication port 11 passes through the flow path 12 and the upper communication port 1
From 0 to the combustion chamber 1 again, and a part of it flows into the injection port 40.
It is recirculated along with the air A injected from the inside of the combustion chamber 1 and the rest is mixed with the combustion gas that has risen upside down in the combustion chamber 1 and is exhausted through the heat storage body 22. Here, the combustion gas C flowing into the combustion chamber 1 again from the upper communication port 10 through the flow path 12.
Is cooled by convective heat transfer while passing through the flow path 12 at the back of the water pipes 4 ,. For example, the temperature of the combustion gas whose temperature has dropped to about 1000 ° C. at the bottom of the combustion chamber further decreases while passing through the flow path 12, and when it flows back into the combustion chamber 1 from the upper communication port 10, the temperature becomes about 200 ° C. Has gone down. Therefore, the combustion gas in the vicinity of the burner firing port is diluted with the lowered temperature combustion gas to lower the temperature, and the temperature of the combustion gas can be entirely lowered without generating a local high temperature region. Further, a part of the combustion gas flowing into the combustion chamber 1 again is accompanied by the combustion gas C injected from the burner system 20 to increase the volume of the combustion gas C, and even if the combustion chamber 1 is deep, the flame rises. Combustion chamber 1 to prevent
The combustion gas C reaches the bottom of the combustion chamber 1 and is heated uniformly in the vertical direction of the combustion chamber 1. Moreover, at this time, the NOx can be reduced by recirculating the combustion gas C. In addition, the increase in the amount of combustion gas circulating in the combustion chamber also increases the amount of combustion gas C flowing in the flow passage 12 at the back of the water pipes 4, ..., 4, so that the vicinity of the lower communication port 11 and the vicinity of the upper communication port 10 are increased. The gas temperature difference between and becomes small, and the amount of heat transfer to the water pipes 4, ..., 4 and the boiler water 15 can be made large, so that the heat transfer surface area can be made small. on the other hand,
The combustion chamber 1 passes through the flow path 12 between the water pipe 4 and the combustion chamber wall surface 3.
A part of the combustion gas C having a temperature of about 200 ° C that has recirculated to the upper part of the combustion chamber 1 reversely rises at the bottom of the combustion chamber 1 and has recirculated in the furnace
It is mixed with a part of a large amount of combustion gas C near 000 ° C. and is exhausted as an exhaust gas at about 900 ° C. In the illustrated state, the heat storage section 3 connected to the combustion gas exhaust system 43
1 is exhausted from the injection port 40 communicating with 1.

Here, the switching between the combustion air and the combustion gas flowing through the heat storage body 32 is, for example, 10 seconds to 90 seconds, preferably 1 second.
It is performed at intervals of about 0 to 20 seconds, or the heat storage body 22
The exhaust gas E discharged via the exhaust gas has a predetermined temperature, for example, 20
Perform when the temperature reaches 0 ° C.

First, in the state of FIG. 2, the entrance / exit means 2
When the air A is introduced into the air supply chamber 23a of No. 3, the air A
Is the second chamber 29c of the distribution chamber 27 through the air supply communication hole 32.
To the chamber / compartment 32 of the corresponding heat storage body 22. At this time, the corresponding compartment / chamber 32 of the heat storage body 22
Is heated by the heat of the high-temperature exhaust gas E that has passed before the switching, the passing air A takes away the heat of the heat storage body 22 and has a high temperature near the temperature of the exhaust gas that has heated the heat storage body 22. Then, from around the fuel nozzle 21 arranged in the center of the heat storage body 22, the fuel is directly injected into the combustion chamber 1 substantially in parallel to the fuel F (state of (A) in FIG. 5). On the other hand, in the corresponding section 31 of the heat storage body 22 communicated with the exhaust chamber 23b of the inlet / outlet means 23 through the exhaust communication hole 26, the exhaust gas E in the combustion chamber 1 is generated by the action of the induction fan of the exhaust system 43.
Is introduced. Then, the exhaust gas E whose temperature has been lowered by heating the section 31 of the heat storage body 22 flows into the first chamber 29b of the distribution chamber 27, and then the exhaust communication hole 2
Then, the gas is discharged to the exhaust chamber 23b via No.6.

Next, when the switching means 24 is continuously or intermittently rotated clockwise from the state shown in FIG.
First, the exhaust communication hole 26 has the third chamber 29 of the distribution chamber adjacent on the left.
As a result, the first chamber 29b and the third chamber 29a simultaneously communicate with the exhaust chamber 23b. Therefore, the exhaust gas E in the combustion chamber 2 passes through the two compartments 31 and 30 of the heat storage body 22 and then flows into the first chamber 29b and the third chamber 29a of the distribution chamber 27, and both chambers 29a, 29a, Exhaust communication hole 2 at 29b
It flows out to the exhaust chamber 23b connected via 6. And it is exhausted. After that, the exhaust communication hole 26 is completely switched to the third chamber 29a (the part that was an empty chamber indicated by reference numeral 30 in FIG. 2), and then the air supply that has been occupied in the second chamber 29c. The communication hole 25 for the first chamber 29b (see FIG. 2).
In the room portion indicated by reference numeral 31),
The second chamber 29c (the chamber indicated by reference numeral 32 in FIG. 2)
The area partitioned by is an empty room. In other words, the exhaust gas E is flown into the vacant chamber 30 where the fluid has not been flown until now,
The air A is made to flow into the chamber 31 in which the exhaust gas E has been made to flow, and the fluid is not made to flow in the chamber 32 in which the air A has been made to flow. Accordingly, the heat storage body 22 is heated by the heat of the exhaust gas E, and the air A passing through the heated heat storage body 22 is warmed by the heat of the heat storage body 22. At this time, the switching of the fluid flow is performed while communicating with each of the two chambers when the vacant chamber 30 is used, so that the fluid flow is not interrupted. Then, the exhaust gas E is sequentially switched to the air A next to the exhaust gas E without interruption. Therefore, the combustion air A passes through the heated heat storage body 22 and becomes hot air having a high temperature close to the exhaust gas temperature and is supplied into the combustion chamber 2 (state (B) of FIG. 5). Therefore, by continuous or intermittent rotation of the switching means 24, (A) of FIG.
As shown in (C), the position at which the air A is injected sequentially changes in the circumferential direction, and the flame rotates in the circumferential direction in the combustion chamber 1.

Although the above-described embodiment is a preferred embodiment of the present invention, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, in this embodiment, the fixed heat storage body 2
For 2, the air supply system 41 and the exhaust system 43 are alternately switched and connected by the flow path switching means 24. However, by rotating the heat storage body itself between the exhaust system and the air supply system, The structure may be such that the flow of exhaust gas and air relative to the heat storage body is switched relatively.

Further, not only the combustion air but also the fuel may be switched at the same time so that a pair of burners are alternately burned and exhausted through the regenerator of the burner which is not burning. For example, although not shown, two burner bodies each having a built-in heat storage body and an integrated heat storage body and a burner are combined, and a pair of burners are alternately burned to stop combustion. It is also possible to employ a burner and a heat storage body capable of discharging combustion gas. The heat storage body / burner throat of the pair of burners is connected to an air supply system and an exhaust system via, for example, a four-way valve, and selectively connected to either the air supply system or the exhaust system by switching the four-way valve. . Then, one burner is provided so as to supply air through the heat storage body, while the other burner is provided so as to discharge combustion gas through the heat storage body. Also,
The fuel is also supplied alternately to the pair of burners using, for example, a three-way valve.

[0032]

As is apparent from the above description, in the small once-through boiler of the present invention, a part of the combustion gas passes through the flow passage on the back side of the water pipe group and then flows into the combustion chamber from the upper communication port again. As a result, the flame and combustion gas near the burner firing port are diluted by the gas whose temperature has been lowered used for radiative heat transfer and convective heat transfer, and the temperature is lowered without generating a local high temperature range. Overall, the temperature of the combustion gas in the combustion chamber can be raised. Therefore, it is possible to reduce the boiler size by increasing the heat load of the combustion chamber. Further, the boiler water flowing in the water pipe is heated by the heat transfer from the flame and the radiant heat from the combustion gas on the inner heat transfer surface, and the flow path between the water pipe group and the combustion chamber furnace wall is heated on the outer heat transfer surface. It is heated by convective heat transfer from the flowing combustion gases. Therefore, even if the combustion chamber is the same size as the conventional one, if the same amount of steam is obtained, it can be made more compact and cheaper than the conventional boiler, and if it has the same heat transfer surface area. Makes it possible to increase the amount of steam compared to conventional boilers.

Further, a part of the combustion gas flowing into the combustion chamber again through the flow path between the water tube group and the combustion chamber furnace wall is accompanied by the combustion air injected into the combustion chamber to increase the volume of the combustion gas. Even when the combustion chamber is deep, the flame is prevented from rising and the combustion gas reaches the bottom of the combustion chamber to uniformly heat the combustion chamber in the vertical direction. Moreover, at this time, the NOx can be reduced by recirculating the combustion gas. Further, an increase in the amount of combustion gas that circulates in the combustion chamber and the flow passage at the back of the water pipe reduces the temperature difference between the inlet side and the outlet side of the flow passage, so the amount of heat transfer to the water pipe can be increased, The heat transfer surface area can be reduced when the same amount of steam is obtained.

In addition, according to the present invention, the heat of the combustion exhaust gas is recovered in the heat storage body and the combustion exhaust gas is exhausted to the atmosphere at a relatively low temperature, while the recovered heat is used to preheat the combustion air to a high temperature. And then back into the combustion chamber again,
In addition to having a good heat balance, steam can be generated even with a small amount of fuel, and running costs can be greatly reduced compared to conventional cases.

Further, in the case of the second aspect of the invention, since combustion is not interrupted only by switching the flow of the combustion exhaust gas and the combustion air without switching the fuel, pressure fluctuations and temperature distribution irregularities in the combustion chamber occur. Less.

Further, in the case of the boiler of the present invention according to claim 3,
Combustion air is supplied to the fuel nozzle in such a manner that it rotates in a circumferential direction around the fuel nozzle, and the flame rotates in a circumferential direction in the combustion chamber, so that the combustion chamber can be uniformly heated. . Since the flame position changes frequently, the heat pattern in the combustion chamber can be made more uniform, and uneven heating can be reduced.

Further, in the boiler of the present invention, when a pair of burners are alternately switched for a short time for combustion, the flame position changes frequently, so that the heat pattern in the combustion chamber can be made more uniform, and uneven heating can be reduced. Because you can
The fluctuation of the heat load of the furnace is small, and the state of the boiler water in the water pipe is uniform, and there is no possibility that the water pipe is locally damaged and the water pipe is damaged.

[Brief description of drawings]

FIG. 1 is a central longitudinal sectional view showing an embodiment of a small once-through boiler of the present invention.

FIG. 2 is a principle diagram of a switching means of a heat storage type burner system used in the small once-through boiler of FIG.

FIG. 3 is a development view showing an embodiment of a water pipe of the small once-through boiler of the present invention.

FIG. 4 is a development view showing another embodiment of the water pipe.

5 is an operation (A) in which the flame rotates in the circumferential direction in the heat storage type burner system used in the embodiment of FIG.
It is explanatory drawing of- (C).

FIG. 6 is a cross-sectional view of a combustion chamber of a conventional boiler.

FIG. 7 is a vertical sectional view showing a case where a heat storage type burner system is applied to a combustion chamber of a conventional boiler.

[Explanation of symbols]

 1 Combustion Chamber 2 Furnace Body 3 Combustion Chamber Wall Surface 4 Water Pipe 10 Upper Communication Port 11 Lower Communication Port 12 Flow Path 20 Thermal Storage Burner System 21 Fuel Nozzle 22 Thermal Storage 24 Switching Means 41 Combustion Air Supply System 42 Fuel Supply System 43 Exhaust System A Combustion air C Combustion gas E Exhaust gas F Fuel

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhisa Mitani 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (4)

[Claims] 1. A small once-through boiler in which a water pipe is installed on a peripheral wall of a combustion chamber so that boiler water flows through the water pipe.
The combustion air is supplied and the combustion gas is discharged through the heat storage body, and the flows of the combustion gas and the combustion air relative to the heat storage body are relatively switched to supply the combustion air through the heat storage body heated by the heat of the combustion gas. At least one heat storage type burner system configured as described above is disposed in the combustion chamber, and the water pipe group is installed away from the combustion chamber wall surface to form a flow path between the back surface of the water pipe group and the combustion chamber wall surface. on the other hand,
A communication port through which combustion gas passes is formed between the water pipes adjacent to the upper and lower end portions of the water pipe group, and a part of the combustion gas is provided so as to pass through the flow path on the back side of the water pipe group. A small once-through boiler, characterized in that a part of the above flows into the flow path from the lower communication port, rises, and then flows into the combustion chamber again from the upper communication port. 2. The regenerative burner system is configured to continuously inject fuel from the same fuel nozzle without switching fuel and relatively switch the flow of combustion exhaust gas and combustion air with respect to the heat storage body. Claim 1 characterized by
The small once-through boiler described. 3. A regenerator type burner system is divided into three or more chambers in the circumferential direction evenly and allows a fluid to pass through each chamber in the axial direction, and a heat accumulator which penetrates the center of the regenerator into the combustion chamber. An inlet / outlet unit having a fuel nozzle for directly injecting fuel, an air supply chamber connected to a combustion air supply system, and an exhaust chamber connected to a combustion gas exhaust system, and the inlet / outlet unit interposed between the heat storage body The heat storage body and the inlet / outlet means are shut off while rotating continuously or intermittently so that the exhaust chamber and the air supply chamber of the inlet / outlet means are divided into any of the three or more heat storage bodies. It is composed of a switching means that sequentially communicates without overlapping, and continuously injects fuel into the combustion chamber and moves high-temperature combustion air around the combustion chamber from the heat storage body to the combustion chamber in the circumferential direction. While the contract is characterized by direct injection The small once-through boiler according to claim 2. 4. The regenerative burner system is characterized in that a pair of burners, each equipped with a regenerator, are burned alternately in a short time and exhausted via the regenerator of the unburned burner. The small once-through boiler described in 1.